Symbol
Mo
  
Cr
  
Period Number
5
  
4
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
Im_ 3m
  
Im_ 3m
  
Interesting Facts
- Molybdenum is highly reactive metal, hence not found free in nature .
- Till 18th century Molybdenum element were often mistaken as a carbon or Lead.
  
- Chromium is highly reactive, hence it is not found free in nature.
- Ores of Chromites mineral are the major source of Chromium metal.
- Almost 90% leather tanning is done with the help of chromium.
  
Sources
Found in Minerals, Mining, Ores of Minerals
  
Found in Minerals, Mining, Ores of metals, Ores of Minerals
  
History
  
  
Who Discovered
Carl Wilhelm Scheele
  
Louis Nicolas Vauquelin
  
Discovery
In 1778
  
In Between 1797 - 1798
  
Abundance
  
  
Abundance In Universe
1.5 * 10-3 %
  
7
Abundance In Sun
~0.0000009 %
  
19
Abundance In Earth's Crust
Uses & Benefits
- Its alloys are used to make engine parts, drills, saw blade, etc.
- Lubricant additive made up of Molybdenum disulfide is commonly used in the industry. It is also used as a catalyst.
  
- It is used to harden the steel and produces a stainless steel and other various alloys.
- It is also used to give proper finish to polished mirrors. Its chromium plates are used in bathroom fittings.
  
Industrial Uses
Aerospace Industry, Electrical Industry, Electronic Industry
  
Automobile Industry, Chemical Industry
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys
  
Alloys
  
Biological Properties
  
  
Toxicity
Toxic
  
Highly Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.00 Blood/mg dm-3
  
31
0.11 Blood/mg dm-3
  
12
In Bone
0.70 p.p.m.
  
18
0.33 p.p.m.
  
21
Melting Point
1,857.00 °C
  
14
Boiling Point
2,672.00 °C
  
39
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Gray
  
Silver
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
1,370.00 MPa
  
7
Vickers Hardness
1,400.00 MPa
  
6
1,060.00 MPa
  
10
Speed of Sound
5,400.00 m/s
  
6
5,940.00 m/s
  
5
Optical Properties
  
  
Reflectivity
Not Available
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Mo
  
Cr
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
684.30 kJ/mol
  
37
26,130.00 kJ/mol
  
1
2nd Energy Level
1,560.00 kJ/mol
  
37
28,750.00 kJ/mol
  
1
3rd Energy Level
2,618.00 kJ/mol
  
99+
34,230.00 kJ/mol
  
1
4th Energy Level
4,480.00 kJ/mol
  
26
37,066.00 kJ/mol
  
1
5th Energy Level
5,257.00 kJ/mol
  
32
97,510.00 kJ/mol
  
1
6th Energy Level
6,640.80 kJ/mol
  
22
105,800.00 kJ/mol
  
1
7th Energy level
12,125.00 kJ/mol
  
13
114,300.00 kJ/mol
  
1
8th Energy Level
13,860.00 kJ/mol
  
16
125,300.00 kJ/mol
  
1
9th Energy Level
15,835.00 kJ/mol
  
16
134,700.00 kJ/mol
  
1
10th Energy Level
17,980.00 kJ/mol
  
18
144,300.00 kJ/mol
  
1
11th Energy Level
20,190.00 kJ/mol
  
17
26,130.00 kJ/mol
  
12
12th Energy Level
22,219.00 kJ/mol
  
15
28,750.00 kJ/mol
  
13
13th Energy Level
26,930.00 kJ/mol
  
13
34,230.00 kJ/mol
  
10
14th Energy Level
29,196.00 kJ/mol
  
13
37,066.00 kJ/mol
  
12
15th Energy Level
52,490.00 kJ/mol
  
7
97,510.00 kJ/mol
  
1
16th Energy Level
55,000.00 kJ/mol
  
8
105,800.00 kJ/mol
  
2
17th Energy Level
61,400.00 kJ/mol
  
9
114,300.00 kJ/mol
  
3
18th Energy Level
67,700.00 kJ/mol
  
9
125,300.00 kJ/mol
  
4
19th Energy Level
74,000.00 kJ/mol
  
9
134,700.00 kJ/mol
  
5
20th Energy Level
80,400.00 kJ/mol
  
10
144,300.00 kJ/mol
  
7
21st Energy Level
87,000.00 kJ/mol
  
9
157,700.00 kJ/mol
  
7
22nd Energy Level
93,400.00 kJ/mol
  
7
166,090.00 kJ/mol
  
6
23rd Energy Level
98,420.00 kJ/mol
  
6
Not Available
  
24th Energy Level
104,400.00 kJ/mol
  
2
Not Available
  
25th Energy Level
121,900.00 kJ/mol
  
1
Not Available
  
26th Energy Level
127,700.00 kJ/mol
  
1
Not Available
  
27th Energy Level
133,800.00 kJ/mol
  
1
Not Available
  
28th Energy Level
139,800.00 kJ/mol
  
1
Not Available
  
29th Energy Level
148,100.00 kJ/mol
  
1
Not Available
  
30th Energy Level
154,500.00 kJ/mol
  
1
Not Available
  
Electrochemical Equivalent
0.89 g/amp-hr
  
99+
0.32 g/amp-hr
  
99+
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Kr] 4d5 5s1
  
[Ar] 3d5 4s1
  
Crystal Structure
Body Centered Cubic (BCC)
  
Body Centered Cubic (BCC)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
9.40 cm3/mol
  
99+
7.23 cm3/mol
  
99+
Adjacent Atomic Numbers
  
  
Valence Electron Potential
88.60 (-eV)
  
13
170.00 (-eV)
  
4
Lattice Angles
π/2, π/2, π/2
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Not Available
  
Density
  
  
Density At Room Temperature
10.28 g/cm3
  
36
7.19 g/cm3
  
99+
Density When Liquid (at m.p.)
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
Ductile, Weldable
  
NA
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Antiferromagnetic
  
Electrical Properties
  
  
Electrical Property
Semiconductor
  
NA
  
Resistivity
53.40 nΩ·m
  
99+
125.00 nΩ·m
  
27
Electrical Conductivity
0.19 106/cm Ω
  
11
0.08 106/cm Ω
  
25
Electron Affinity
71.90 kJ/mol
  
14
64.30 kJ/mol
  
15
Specific Heat
0.25 J/(kg K)
  
21
0.45 J/(kg K)
  
12
Molar Heat Capacity
24.06 J/mol·K
  
99+
23.35 J/mol·K
  
99+
Thermal Conductivity
138.00 W/m·K
  
12
93.90 W/m·K
  
17
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
4.80 µm/(m·K)
  
99+
4.90 µm/(m·K)
  
99+
Enthalpy
  
  
Enthalpy of Vaporization
594.10 kJ/mol
  
8
348.80 kJ/mol
  
24
Enthalpy of Fusion
27.61 kJ/mol
  
5
15.31 kJ/mol
  
20
Enthalpy of Atomization
653.00 kJ/mol
  
7
397.50 kJ/mol
  
21
Standard Molar Entropy
28.70 J/mol.K
  
99+
23.80 J/mol.K
  
99+